title: Electrical conductivity of microwave heated polyaniline nanotubes and possible mechanism of microwave absorption by materials.
abstract: In the course of experiments to perform deprotonation and carbonization of doped polyaniline (PANI) nanotubes (NTs) by irradiating directly 2.45 GHz microwave (MW) in our microwave heating system (MWHS), we have discovered that the PANI-NTs self heat by absorbing the MW but the temperature of the PANI-NTs stops rising around 300 degrees C in spite of the heightened MW power Furthermore, we have found that the MW irradiated PANI-NTs have transferred from electrical conductor to insulator depending on the temperature of the PANI-NTs. By measuring electron spin resonance (ESR) spectra of the MW heated PANI-NTs, the existence of the unpaired electrons is shown to have a strong correlation between the degree of MW absorption and the transition in the electrical conductivities. In order to deprotonate and carbonize further the PANI-NTs, we have performed heat treatment for the PANI-NTs up to a temperature (T(HT)) of about 1200 degrees C in the same MWHS using carbon fiber which self heats by absorbing MW. The chemical transformations in the PANI-NTs induced by the heat treatments are discussed by measuring the X-ray photoelectron spectroscopy (XPS) spectra. Finally, the temperature dependence of electrical conductivities of the PANI-NTs are measured in order to investigate the mechanism of electrical conduction of the heat treated PANI-NTs.
authors.affiliation: Faculty of Textile Science and Technology, Shinshu University, Ueda, Nagano 386-8567, Japan.
authors.forename: Takahiro
authors.initials: T
authors.lastname: Murai
authors.forename: Ryo
authors.initials: R
authors.lastname: Fukasawa
authors.forename: Tohru
authors.initials: T
authors.lastname: Muraoka
authors.forename: Hiroyuki
authors.initials: H
authors.lastname: Takauchi
authors.forename: Yasuo
authors.initials: Y
authors.lastname: Gotoh
authors.forename: Tokihiro
authors.initials: T
authors.lastname: Takizawa
authors.forename: Takehiro
authors.initials: T
authors.lastname: Matsuse